Airbag Light Failed TÜV Inspection: What to Do?
Airbag Warning Light at MOT: Why Do You Fail?
A continuously illuminated airbag warning light is classified as a major defect during the main inspection (MOT). The inspector refuses the MOT certificate because the restraint system is not functioning correctly – in an emergency, airbags and seatbelt pretensioners might not deploy.
Since 2006, the MOT has been testing safety systems electronically. Simply removing or disconnecting the warning light is not sufficient – the inspector reads the fault memory via the OBD interface and immediately detects stored errors. Only a professional repair of the actual cause will result in passing.
Difference Based on First Registration
For vehicles first registered on or after January 1, 2018, an illuminated airbag control light is a direct reason for rejection. For older vehicles, the defect is noted in the inspection report and can also lead to refusal of the certificate if a safety risk exists.
What Happens After Failing?
After failing the MOT, you have one month to take a retest. Within this period, you must fix the defect and present the vehicle again. The retest costs between 15 and 30 euros – significantly less than a complete new MOT.
| Step | What Happens | Deadline / Costs |
|---|---|---|
| MOT Not Passed | Inspection report with major defect | – |
| Repair | Have the cause fixed at a specialist workshop | Within 1 month |
| Retest | Only the reported defect is inspected | 15–30 € |
| Missed Deadline | Complete MOT must be repeated | Full MOT fee again |
Important: The retest does not have to be done by the same inspector or the same inspection organization. You can freely choose between TÜV, DEKRA, GTÜ, and KÜS.
What Causes Are Behind the Airbag Light?
The most common causes of an illuminated airbag warning light are a faulty airbag control unit with stored crash data, a defective seat occupancy mat, a broken crash sensor, a faulty seatbelt pretensioner, or a broken spiral cable. Fault diagnosis using a diagnostic device shows the exact cause.
| Cause | Description | Frequency |
|---|---|---|
| Crash Data in Control Unit | Data stored after an accident blocks the system | Very Common |
| Seat Occupancy Mat Defective | Sensor under seat cushion does not detect passenger | Very Common |
| Crash Sensor Defective | Side impact sensor damaged by corrosion | Common |
| Seatbelt Pretensioner Deployed | Seatbelt pretensioner deployed after accident not replaced | Common |
| Spiral Cable Broken | Flat ribbon cable in steering wheel broken | Moderate |
| Loose Connector | Contact under seat or at control unit oxidized | Moderate |
What to Do If the MOT Flags the Airbag Light?
The first step is a professional fault diagnosis at the workshop. Using a diagnostic device, the exact fault code is read, which narrows down the cause. Then the faulty component is repaired or replaced and the fault memory is cleared. After that, you can go for the retest.
- Read Fault Code: Have the fault memory of the airbag control unit read at the workshop
- Identify Cause: The fault code shows which component is affected
- Perform Repair: Replace the faulty part or have crash data cleared
- Clear Fault Memory: Reset all codes after successful repair
- Function Test: Check whether the warning light goes out after ignition
- Retest: Present the vehicle to the MOT within the one-month deadline
Clearing Crash Data as the Most Common Solution
In many cases – especially with used vehicles – crash data from a previous accident is still stored in the control unit. Clearing this data by a specialist workshop restores full functionality of the airbag system without needing to completely replace the control unit. Airbag24 offers this repair for all makes and models – MOT-safe and with over 20 years of experience.
Can You Simply Have the Airbag Light Cleared?
Simply clearing the fault memory without addressing the cause is not a permanent solution. If a real defect exists, the warning light will return after a short time. Only if the cause has been fixed – whether through repair, replacement, or crash data clearing – will the light go out permanently.
With a loose contact or temporary fault, clearing the fault memory may be sufficient. However, if there is a permanent defect in a sensor, control unit, or wiring, the system will immediately store the error again. A reputable workshop will therefore always clarify the cause first before clearing the memory.
What Does the Repair Cost Before the Retest?
Repair costs depend heavily on the cause. Simply clearing the fault memory costs only a few euros, while replacing a control unit or sensor is significantly more expensive. A repair at Airbag24 is up to 50% cheaper than buying a new control unit.
| Repair | Costs (approx.) |
|---|---|
| Clear Fault Memory (without defect) | 10–50 € |
| Clear Crash Data (Control Unit) | Price in Shop |
| Replace Crash Sensor | Price in Shop |
| Replace Seat Occupancy Mat | Price in Shop |
| Replace Seatbelt Pretensioner | Price in Shop |
| Replace Spiral Cable | Price in Shop |
Find exact prices for your vehicle model in our shop. At Airbag24, you get professional repairs and matching spare parts for all makes – we're happy to help.
Frequently Asked Questions About the Airbag Light at MOT
Here you'll find answers to the most important questions about the airbag warning light and the main inspection.
Does the Airbag Light Only Come On Briefly – Is That a Problem at MOT?
No. A brief illumination after starting (2-5 seconds) is normal and shows the system's self-test. It only becomes problematic if the light stays on continuously or doesn't come on at all – both indicate an error.
Can I Still Go to MOT with the Airbag Light On?
You are allowed to drive to your MOT appointment, but you will very likely fail. It makes more sense to have the error fixed beforehand and then go for the MOT – this saves you the cost of the retest.
What Happens If I Miss the Retest Deadline?
If the one-month deadline passes without a retest, you must undergo the complete main inspection again and pay the full fees once more. Additionally, a warning fine of at least 15 euros may be imposed.
Does the MOT Detect If the Airbag Light Has Been Tampered With?
Yes. The inspector performs a lamp test and reads the fault memory electronically. A disconnected or bypassed light is immediately noticed because it doesn't briefly illuminate when the ignition is turned on. Tampering with the airbag system is also punishable by law.